1. Technical Field
The present invention relates to a semiconductor device that includes a semiconductor element the properties of which can change in response to light.
2. Related Art
As semiconductor elements the properties of which change in response to light, there are a MOS transistor, a nonvolatile memory having a floating gate electrode, and the like. These semiconductor elements, especially when mounted by using COG mounting methods, such as bear chip mounting, receive light, causing fluctuation of an on/off property in the case of a MOS transistor or causing escape of electron infused in the floating gate electrode in the case of a nonvolatile memory. For preventing the fluctuation of semiconductor element properties, a light shielding layer is set up on the area on which these devices are set up to prevent light from being irradiated.
JP-A-2003-124363 is an example of light shielding technologies. In JP-A-2003-124363, a memory cell array effective area and a light shielding area are set up in a manner that the latter surrounds the periphery of the former, with a via layer and a contact layer set up at different levels on the light shielding area. It is a technology of inhibiting entrance of light from the lateral direction and from the oblique direction by staggeredly placing the via layer and the contact layer.
However, even if a light shielding area is set up in a manner of surrounding the periphery of a memory cell array effective area so as to reduce entrance of light from the lateral direction and from the oblique direction, there are still needs, for example, to draw out a wiring, such as a signal wire, from the memory cell array effective area to the outside of the light shielding area. Therefore, there are cases where the memory cell array effective area can not be completely surrounded by the via layer and the contact layer that are set up staggeredly.